Electricity-meter.



No. 656,545.- Patented Aug. 2|, I900.

a. HOOKHAM.

ELECTRICITY METER.

App1ication filgd July 9, 1900.)

(No Model.) 5 Sheets8heet l.

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No. 656,545. Patented Aug. 2|, I900. 03. HUOK'HAM.

ELECTRICITY MET'ER.

(Application filed m 9, 1900. (No Model.) 5 Sheets-Sheet 2.

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No. 656,545. Patented Aug. 2|, I900. e. HDOKHAM. ELECTRICITY METER.

(Application filed July 9, 1900.)

5 sheets sheet 3,

(No Model.)

No. 656,545. Patented Aug. 21, 1900. a. HOOKHAM.

ELECTRICITY METER.

(Application filed July 9, 1900.

5 Sheets-Sheet 4.

(No Model.)

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No. 656,545. Patented Aug. 2|, I900. G. HOOKHAM. ELECTRICITY METER.

(Application filed July 9, 1900.)

5 Sheets-8heet 5.

(No Model.)

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UNITED STATES PATENT OFFICE.

cEoReE IIOOKIIAM, OF BIRMINGHAM, ENGLAND.

ELECTRICITY-M ETER.

SPECIFICATION forming part of Letters Patent No. 656,545, dated August21, 1900.

Application filed July 9, 1900. Serial No- 2s.027. (No model.)

To aZZ whom it may concern:

Be it known that I, GEORGE Hooxnnmelectrical en gineer,a subject of theQueen of Great Britain and Ireland, and aresident of 4 New Bartholomewstreet, in the city of Birmingham, England, have invented a certain newand useful Improvement in Iillectricity-lVIeters, (for which I have madeapplication for Letters Patent in Great Britain, No. 17,159, hearingdate August 24, 1899,.) of which the following is a specification.

My improvements apply principally to that class of meters in which thedeviations from normal time produced in a pendulum affected by theelectric current (or energy) to be metered are registered. The rate ofsuch a pendulum is generally compared with that of an unaifectedpendulum, and it is essential to accurate registration that when nocurrent is passing the two pendulums should synchronize. This conditionhas been found very difficult to realize, and the principal object ofthe present invention is to secure such synchronism.

My invention consists in automatically synchronizing two pendulums bymeans of a beam or balance gear at periodic intervals in anelectricity-meter, in which registration is effected by deviations fromnormal time produced in one pendulum by the current or energy to bemeasured, neither pendulum being afiected by the current to be measuredduring the said periodic intervals.

It further consists in apparatus adapted to effect this synchronization.

Referring now to the accompanying five sheets of drawings, whichillustrate meters in accordance with my invention, Figure l is afrontelevation of an alternating-current meter having the motor andfront plate removed to show the clockwork. Fig. 2 is a front and Fig. 3a side elevationof the-motor which I prefer to use inalternating-current meters. Fig. 4=is a plan view of the whole meter,including both motor and clockwork. Fig. 5 is a side elevation, and Fig.6 an end elevation, on an enlarged scale, of a switching device adaptedto effect the switching in and out of the shunt-coil atperiodicintervals and also to bring the synchronizing device into andout of operation. Fig. 7 is a diagram of the electric circuits of themeter shown in the previous figures. Fig. 8 is a diagrammatic viewshowing a modified form of meter in which the shuntcoil is fixed to themeter-case and the series coil is carried by the pendulum-bob.

According to my invention as illustrated in the first six figures of thedrawings I ar range two pendulums a and b, a being a free pendulum, andb a pendulum controlled by the current to be measured. The pendulums aresupported on pivots or knife-edges c. Pendulum a is not afiected underany conditions by the current, while pendulum 1) carries a shunt-coil2", which is'acted on by a fixed series coil j, whose terminals areshown at 7.: and Z. These coils may be arranged to afiiect one anotherin any well-known manner-401* example, the series coil j may be placedwith its axis vertical, in which case the coil 2', carried on thependulum I), would be similarly disposed with its axis vertical andwould swing closely over the fixed coilj. Each pendulum carries anescapement-pawl on, whereby it is driven by means of an escapementwheela, spring 0, and gear-wheel 13. (See plan Fig. 4.) These gear-Wheels 12each operate one of the spur-wheels r of the dilferential gear-train.The Wheels 7' each carrycrown-wheels s, which both gear with a commonpinion 2f, carried loose on a staif u, fixed on the axle o. This'axle'12 carries an aluminium disk 10, onwhich rests a similar disk 71, fixedon a spindle 2. The disk It has its spindle 2 guided in a verticalplane. \Vhen inits lowest position, disk It rests on and is rotated bydisk w. On spindle 2 is provided the synchronizing-beam e, which carriesthe very light and nearly close spiral springs f, which are shownexaggerated in diameter in the drawings for the sake of clearness. Theupward projections 61 on the pendulums are formed with edges struck fromthe center of oscillation of the beam 6. A further disk g is provided onthe axis 2, and a lever-arm 3,

pivoted at 4, has a knife-edge block 5, which of gear with the disk 10,thus fixing the beam 6 in position. Then the accelerated or retardedpendulum is not being affected by the current to be measured, the coil 6is energized, and it pulls down the lever 3 by the armature 7, thussetting. the beam 6 free to. be rotated by the differential gear into aposition such as is shown in dotted lines in Fig. 1 to correct want ofsynchronism of the pendulums. The beam e, carried on the spindle 2, hasthe two fine spiral springsf, supported one at each end. These spiralsare closely coiled and of such length that theyoffer a very smallresisting force to deflection. They therefore slightly accelerate thevibration of the pendulnms a and 1), whose extensions 61 strike againstand bend the coils fat each vibration. When the beam is horizontal, thependulums are in perfect synchronism if the periods of vibration of thetwo are the same and the springsfalso are of equal strength. If these benot quite the same, the beam 6 will take up some other position at whichthe pendulums are in perfect synchronism.

I provide the motor shown in plan in Fig. 4 and in separate elevationsin Figs. 2 and 3 to supply driving force to the clocks and also to actas a timekeeper. This motor has two copper disks carried on suitablebearings by spindles 10 and 11, respectively. These disks overlapbetween the pole-pieces 12 and .13 of the two magnets 14 and 15. Thesepole-pieces 12 and magnet 15 are supported by non-magneticdistance-pieces 101 and screws 102. The magnet 14 has a shunt winding orcoil on the bobbin 16. The ends of this shunt-coil 16 are indicated at17 and 18, Figs. 1 and 2. Over the shunt-coil 16 is placed a secondarywinding or coil 19, which is continuous and forms a closed circuit withwindings 20 on the magnet 15. These two magnetic fields produceinteracting eddy-currents in each of the disks 8 and 9, which cause themto rotate in opposite directions, thus driving the pendulums through thepinions 21 and 22 on the motorspindles 10 and 11. These pinions geardirectly with the large toothed wheels 19.

I use a switching device, one form of which is illustrated in Figs. 5and 6, to switch off the current to be measured from the shunt-coil 11and switch in the synchronizing-gear at the proper periodic times forsynchronization of the pendulum. In the form of switching deviceillustrated a pinion 23 is fixed on the gear-wheel spindle of theunaffected pendulum ct. This gears with a large toothed wheel 24, onwhose axle is fixed a disk 25, carrying pins 26 27. The disk rotates inthe direction shown by the arrow 28 and between the pins 29 and 30 on adisk 31. The disk 31 is fixed to the axle of a cylindrical plug tomblerswitch 32, carried in bearings 33. On the other end of the axle ofthe tumbler-switch 32 a lever-.34 is fixed, carrying a tumblingweight35. The axisof the tumbler-switch and its disk 31 is above the level ofthe axis of the disk 25, so that the pins 26 27 may clear the pins 29and 30 in their highest positions. The cylindrical plug-switch is ofinsulating material, having contact-pieces 36 and 37 let into thesurface at the proper points, on which bear spring contact-pieces 38,39, and 40. The disk-25 and its pins must be geared so as to make acomplete revolution in each four minutes if the tumblerswitch is to beoperated at periodic intervals of two minutes. When the pin 26, say,comes into engagement with the pin 29, it gradually lifts the latteruntil the tu mbler-weight passes over the center, when it falls over andchanges the electrical connections of the meter.

In Fig. 7 is shown diagrammatically the electric circuits within themeter. The arrangement is the same as in Fig. 1, except that in thelatter figure the secondary circuit of the motor is omitted for the sakeof clearness. The series current enters by terminal it and passingthrough the series coilj leaves by terminal Z. In Figs. 1 and 7 thecircuits are shown in the position when the pendulum is not affected bythe current to. be measuredthat is, when there is no current throughcoil i. The shunt-current then passes into the meter by the terminal 41,thence by wire 43 through the motor shunt-coil 16, entering at 17 andleaving at end 18. It then passes, by the wire 44, to the coil 6, fromwhich, by the wire 45, it passes to the tumbler-switch terminal 40. Herethe contactpiece 37 connects with the common returnterminal 39, which inturn connects with wire 46, conveying the current to the secondshunt-terminal 42. The secondary circuit of the shunt magnet-coil 16 isindicated at 105. This circuit isclosed through the wire'106, passingaround the upper magnet 15 and back to the coil at 107. WVhen thesynchronizing period of, say, two minutes has elapsed, thetumbler-switch changes the shunt connections, putting in the pendulumshunt-coil i and taking out the coil 6. This then releases itsarmature7, which is over-balanced. by the counterweight-103. Thelever-arm 3 then by means of its knife-edge block lifts up the disk g,and thereby the beam e, which is thus held in the angular positiondetermined by the last synchronizing operation. The pivots 2 of the beam6 are provided with vertical guides, as shown at 108, Fig. 1. Whenreversal of the electrical connections has taken place by means of thetumbler-switch, the shunt-current flows, as before, through the shuntmagnet-coil 16 and thence, by the wire 44, to the point 47, where abranch wire 48 passes off to the pendulum shunt-coil 2', whence itpasses, by way of the wire 49, to the terminal 38 and then through thecontact-piece 36 and wire 46 to the second shunt-terminal 42. Thependulum Z2 is now affected by the current to be metered, and a recordtakes place on the index 104, connected with the spindle v of thedifferential gear. At the end of the next two minutes reversal of thecircuit connections again takes place,the pendulum I) being againunaffected and the electromagnet 6 energized. The disk his thus againlowered, and any difference in the rates of the two pendulums will causethe differential gear to rotate, carrying with it the disk w. This diskto thus drives the disk It and with it the beam 6, which carries thesprings f into a position in which they correct the error of synchronismby accelerating the slow pendulum and slowing up the pendulum which isbeating too fast. I find that by this means the want of synchronismbetween the pendulums can be corrected for the purposes of anelectricity-meter. For the sake of preventing sparking I prefer toarrange the contact-pieces 36 and 37 to overlap, so that the two coils iand 6, which may be of nearly the same resistance, will be for a veryshort interval in parallel with one another. The shunt-circuit istherefore never broken in the operation of the meter, and the coil 16 isalways in circuit. I may in some cases arrange the motor shunt-coil 16on a separate circuit which is then not connected with thetumbler-switch- In Fig. 8 I have shown an arrangement of meter in whichthe series coil is carried on the pendulum b and the shunt-coil z isfixed. With this arrangement the meter becomes independent of the earthsmagnetic field and within the limits of its range for all externalmagnetic influences. In this form of meter I use thin flat copper bands108 of zigzag form and of suitable length to lead in the current to thecoil on the moving pendulum b. I also cause these to be fixed to a pointvery near to the pendulum-pivot,so that an exceedingly-small motion ofthe connecting-bands 108 will be required. In all other respects thearrangements shown in Fig. 8 correspond with that in Figs. 1 to 7.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. In electricity-meters in which two pendulums are compared, one beingaifected at periodic intervals by the current to be measured and theother heating normal time, a

synchronizing device consisting of a balanceing pendulum at periodicintervals, and synchronizing means brought into operation at periodsalternating with periods during which the current or energy alfects oneof the pendulums substantially as described.

In two-pendulum electricity-meters, a synchronizing device, consistingof a beam carrying springs, against which projections on the pendulumsvibrate, and whose angularposition is controlled at periodic intervalsfrom the difierential gear connecting the pendulums, for the purpose ofautomatically effecting an acceleration of the slow pendulum, and aretardation of the fast one, till synchronism is obtained substantiallyas described.

4. In electricity-meters in combination two pendulums one uuafiected andacting as a timekeeper the other carrying a coil through which theseries current passes, a drivingmotor, switching means operated by thetimekeeping pendulum at periodic intervals, and synchronizing meansbrought into operation at periods alternating with periods during whichthe current or energy afiects one of the pendulums substantially asdescribed.

In witness whereof I have hereunto set my hand in presence of twowitnesses.

GEORGE HOOKHAM.

Witnesses:

FREDERICK JOHN EDWARDS, HERBERT BOWKETT.

